Hi Yang, On Sun, Jan 23, 2022 at 11:30 AM Hu, Yang (HIU) wrote:

Dear IFEFFIT members,

I am trying to apply the FEFF calculation on Metal-[Fe(CN)6] type materials (in Larch). The calculations were successful with cif files from (K, Na)x(Cu, Ni) [Fe(CN)6] for both C-coordinated Fe and N-coordinated metals, and their results include higher-order paths.

However, the calculation on NaxFe[Fe(CN)6] always gives the warning “…Two atoms very close together. Check input…” and takes long time. The calculated results have some collinear 5- and 6-leg paths with several hundred or even thousand importance value.

I am wondering if it is possible to limit the multiple scattering to a lower order in the calculation (such as suggested in Artemis user guide).

Plus, if I only aim to model the nearest Fe-C and Fe-N for its Fe K-edge spectra, are there any alternative methods for the calculation? — I also would like to ask whether it is meaningful to do this while ignoring those multiple scatterings in this type of materials.

I'm not sure why those (or one of them?) is reporting "atoms too close together". You can control "how far out to go in R" with "RPATH" - is a value that is smaller than the cluster size. That is, you could use something like RPATH 5.25 to consider paths with distance (half-path lengths) up to 5.25 Ang. You can use NLEG to set the maximum number of legs in a mulltiple-scattering path. That is, NLEG 2 would mean "single scattering only", but you might want to actually use 3 or 4. The default is 8 (in Feff8 that is, it is 7 with Feff6). Cheers, --Matt